Muffler for pneumatic pick hammers and like tools



July 24 1951 o. .1.y H. CHI-:RAIN 2,561,726y

MUFFLER FOR PNEUMATIC PICK-HAMMERS AND LIKE TOOLS Filed July 25. 1947 2 Sheets-Sheet l mvg/v70@ 05cm@ @ffm/v HEM" (Mmm/1v @VMM July 24, 1951 o. J. H. CHE-RAIN 2,561,726

MUFFLER FOR PNEUMATIC PICK-HAMMERS AND LIKE TOOLS Filed July 25, 1947 2 Sheets-Sheet 2 Patented July 24,

MUFFLER FOR PN ggssi'gzc EptrTIo PICK HAMMERS AND LIKE TOOLS Oscar Jean Henri Cher-ain, Jemeppe-sur-Meuse, Belgium Application July 25,1947, Serial No. 763,489 In Belgium July 31, 1946 1 Claim.

My invention relates to muiller for pneumatic pick-hammers and like tools and has reference particularly to improvements to said apparatus in order to suppress as far as possible the production of cloud of dust when working with a pick-hamy the turning sleeve in which the needle ts, a piece that forms a fluidtight joint with the needle which passes through it.

A still further object is to provide a needle having a cup-shaped or crescent-shaped cross section, the two cutting edges of which are separated from one another by a single groove.

My invention will be more fully described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a view of the pick-hammer, partly in longitudinal elevation but mainly in section;

Figure 2 is a cross section on the line A B in Figure 1;

Figure 3 is a back view of the handle of the hammer, showing the angular position of the pressure-reducing device in relation to the axial -plane of the hammer;

Figure 4 is a section on the line C--D in Figure 1;

Figure 5 is a plan View of the cutting end of the needle; and

Figure 6 is a section on the line E-F in Figure 5, on a scale twice as large. e

Figure 7 is a plan view on an enlarged scale oi' the perforated ring shown in Figure 1.

Figure 8 is a section on the line G-H of Figure 7.

Figure 9 is a plan view on an enlarged scale of the sieve or strainer shown in Figure 1.

Figure 10 is a section on the line I-J of Figure 9.

The pick-hammer to which the improvements provided by this invention are applied is of a known type, to which of course no claim is made in itself.

According to the invention, the socket or sleeve I of the handle is provided, at the place Iwhere the exhausting of the compressed air into the atmosphere takes place, with a cast-on nozzle or blast-pipe 2, the axis of which makes a definite angle, of 35 degrees for example, with the axis X--Y of the hammer, as indicated in Figure 3.

Into this nozzle 2 is screwed a threaded union or coupling member 3, into which in its turn is screwed, beyond a perforated metallic ring 4, a tubular .body 5 of cast iron, Duralumin or the like, provided internally with triangular ribs 6, so arranged relatively to one another as to form baille plates. At its other end the body 5 terminates in a sleeve or socket l, in which is xed a small sieve or strainer 8. This socket 'I tapers outwards to a beak or jet 9 shaped like the barrel of a whistle, the aperture of which may be cut transversely by a rib.

The compressed air expelled by the distributing valve of the pick-hammer flows through the nozzle 2, encountering a cross-bar I0 inserted in the latter with a, view to deilecting the current of compressed air. Next it enters the body 5, where its pressure is greatly reduced under the influence of the opposite ribs 6, and then of the screen 8, and finally it escapes into the atmosphere through the mouth or jet 9. This air therefore leaves the pick-hammer towards the rear of the latter, but laterally in relation to the workman who is operating it, so that its pressure, being considerably diminished, is insuilicient to cause eddies of air' capable of raising the dust produced .by the hammer and forming whirling eddies that would be injurious to the operator.

With the same end in view the turning sleeve II, which is screwed on to the body I2 of the pickhammer in order to cover the needle I3, is screwthreadedat its end at I4 to receive a conical piece l5 through which the said needle passes. The fluid tightness of the assemblage is ensured on the one hand by an india-rubber ring I6 interposed between the sleeve I I and the conical piece I5, and on the other hand by a ring I1 of metal, anti-friction material or the like between this conical piece and the needle I3.

Finally the needle I 3 itself has only two cutting edges I8, separated from one another on one side by a longitudinal groove I9, the outline of the cross sectionfbeing completed by a substantially semi-circular part 20. This being so, the needle I3, in working, does not produce dust, as is the case with the four cutting edges of the usual needles, but granules, of coal for example, the weight of which is too great for toxic clouds to form under the action of the compressed air, especially at a reduced pressure.

Having thus described my invention, what I claim as new, and desirev to secure by Letters Patent is:

A muiller for pneumatic hammers and like tools, consisting of a hollow body carried by the tool,

Said hollow body having internal baflies and a reduced cross-section at its ends, each of which is provided with a, screen to reduce the pressure of the uid exhaust, a, uid outlet orifice formed in M "fm" '1332.152

4 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS HStewart s Nov. 1'1, 1931 

